Simple Voltmeter

Created: Jul 21, 2014

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Description

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Summary

This circuit can be used to measure the voltage to 15 volts.Using the current from the battery 9 volt,At 23 mA only. Input circuit has a diode, to protect the Return terminal. And input impedance of the circuit, were more than 1 M ohm.
The op – amp number 741 acts as a comparator and serves as the heart of the circuit.When the voltage across the pin emitter-bass of the transistor Q1 is a great value, resistance between the collector and emitter are charged less. Therefore less valuable, and the output of IC1 to pay current LED1 light.When we adjust to the middle leg of VR1 to lower pressure. Until the pin 3 of IC1 is low pressure over the two legs a little.LED1 off, it will be.If we adjust VR1 compared to the pressure they can pretend to know the scale at the VR1.Voltmeter can not be used to measure the pressure of the alternating current (ACV) home.